import 'package:flutter/gestures.dart';
import 'package:flutter/rendering.dart';

/// A "polyfix" [TextSpan] that properly renders Emojis at the correct size
/// and vertical-alignment for the given [style].
///
/// See https://github.com/flutter/flutter/issues/28894
class EmojiTextSpan extends TextSpan {
  EmojiTextSpan({
    required TextStyle style,
    required String text,
    List<TextSpan>? children,
    GestureRecognizer? recognizer,
  }) : super(
            style: style,
            children: _parse(style, text)..addAll(children ?? []),
            recognizer: recognizer);

  static final regex = RegExp(
      r"((?:[\u2700-\u27bf]|(?:\ud83c[\udde6-\uddff]){2}|[\ud800-\udbff][\udc00-\udfff]|"
      r"[\u0023-\u0039]\ufe0f?\u20e3|\u3299|\u3297|\u303d|\u3030|\u24c2|\ud83c[\udd70-\udd71]|"
      r"\ud83c[\udd7e-\udd7f]|\ud83c\udd8e|\ud83c[\udd91-\udd9a]|\ud83c[\udde6-\uddff]|"
      r"[\ud83c\ude01-\ude02]|\ud83c\ude1a|\ud83c\ude2f|[\ud83c\ude32-\ude3a]|"
      r"[\ud83c\ude50-\ude51]|\u203c|\u2049|[\u25aa-\u25ab]|\u25b6|\u25c0|[\u25fb-\u25fe]"
      r"|\u00a9|\u00ae|\u2122|\u2139|\ud83c\udc04|[\u2600-\u26FF]|\u2b05|\u2b06|\u2b07|\u2b1b"
      r"|\u2b1c|\u2b50|\u2b55|\u231a|\u231b|\u2328|\u23cf|[\u23e9-\u23f3]|[\u23f8-\u23fa]"
      r"|\ud83c\udccf|\u2934|\u2935|[\u2190-\u21ff])+)");

  static List<TextSpan> _parse(TextStyle _style, String text) {
    final TextStyle textStyle = _style;

    final emojiStyle = textStyle;

    final spans = <TextSpan>[];

    text.splitMapJoin(
      regex,
      onMatch: (m) {
        try {
          spans.add(TextSpan(text: m.group(1), style: emojiStyle));
        } catch (e) {}
        return '';
      },
      onNonMatch: (s) {
        spans.add(TextSpan(text: s));
        return s;
      },
    );

    return spans;
  }
}
